1. Technical Field of the Invention
The present invention relates to a constant rate discharge apparatus and a constant rate discharge method capable of controlling the rate of a high viscosity material discharged from the apparatus.
2. Prior Art
High viscosity materials such as silicone rubber, epoxy resin, grease and the like are being increasingly used as sealing materials or lubricants applied between mechanical parts since their sealing ability is high and reduction in cost can be achieved. Materials of this type are contained in a container of a material discharge apparatus and discharged from a nozzle by actuation of a pump unit linked with the container.
However, pressure adjustment relies only upon the operator's manual adjustment in the conventional material discharge apparatus since the discharge rate of the material is kept constant by adjustment of the pressure in the cylinder for actuating the pump unit. In this case, problems arise in that the operator must always monitor a pressure meter and pressure adjustment based upon such montoring is dependent upon the operator's skill. In addition, high viscosity materials change their viscosity depending upon both changes in ambient temperature and different production lots. The discharge rate of the material also has a strong tendency to change over time. Accordingly, a considerable burden is imposed on the operator.
There exists an apparatus which is capable of pumping the above-mentioned materials under pressure by means of a servo-motor and the like in order to conduct a constant rate discharge for the above-mentioned materials. Such an apparatus has disadvantages in that its manufacturing cost is high and its structure is complicated. Further, the weight of the discharge apparatus is high. If the discharge apparatus is linked with an application robot, an excessively high load would be disadvantageously applied on the robot.